Method for rendering two output formats simultaneously

ABSTRACT

A method for rendering input data simultaneously into output data ( 10 ) in a first output format and in a second output format, the method including: a) defining a plurality of bands ( 11 - 14 ) constituting the output data ( 10 ); and b) for each specific band ( 11 - 14 ) out of the plurality of bands ( 11 - 14 ): i) generating by a renderer from the input data first output data for the specific band ( 11 - 14 ) in the first output format, i) and generating, from the first output data, second output data for the specific band ( 11 - 14 ) in the second output format.

FIELD OF THE INVENTION

The invention relates to printing images, in particular to renderingimage data in order to print them.

BACKGROUND OF THE INVENTION

In order to produce printed matter such as books, newspapers, packagingmaterial and the like, the involved image data are usually processed bya pre-press workflow system. Such a pre-press workflow system isdisclosed in patent application WO 01/25907. One of the steps in apre-press process is the rendering process, i.e. the translation of theimage data from page description languages like Postscript or PDF toraster data, which are also called bitmap data. The rendering process isperformed by a renderer, also known as the Raster Image Processor orRIP. The input data of the renderer are the image data, the output dataare the bitmap data. The output data of the renderer are sent to adevice such as an imagesetter or a platesetter, which is called in thisdocument the main output device. The output data of the renderer for themain output device are called in this document the main output data. Inan imagesetter, by means of the bitmap data a radiation-sensitive filmis exposed, that is used to obtain a printing plate. In a platesetter,the printing plate is obtained directly, by exposing a printing plateprecursor by means of the bitmap data. The printing plate is then used,e.g. in an offset press, to produce the printed matter. Very often,prior to final output the data are checked by means of a proofing device(also called proofer). The proofing device requires data in anotherformat, e.g. at a lower resolution, than the main output device.

U.S. Pat. No. 5,625,766 discloses a software based proofing methodallowing to proof and measure registration between the front and theback side of a press sheet by displaying, on a color monitor, both sidessuperimposed on each other. The data to be displayed is taken from a lowresolution raster image processor identical in operation to a fullresolution raster image processor used to generate the output for themain output device.

In another prior art implementation, the main output data of therenderer is first stored on disk. In the usual case of color output, thecolor separation files are stored on a plane by plane basis; typicallyfirst the cyan separation is generated by the renderer and stored ondisk, followed by magenta, yellow, black and optionally by spot colors.When requesting the proof, the main output data is read from disk (asmentioned, typically data for four color planes and for an additionalplane per spot color), the color separations are recombined and the datafor the proofing device is generated from the high resolution screeneddata intended for the main output device.

For more information on proofing, rendering, imposition and otherrelevant terms, we refer to U.S. Pat. No. 5,625,766 mentioned alreadyabove.

There is still a need for an improved method for rendering output datain two different formats from input data.

SUMMARY OF THE INVENTION

The present invention is a method for generating output data in twodifferent output formats as claimed in independent claim 1. Theinvention also includes a system and a computer program implementing themethod. Preferred embodiments of the invention are set out in thedependent claims.

In a method in accordance with the invention, the two output formats aregenerated virtually simultaneously. The main output data has a formatthat is typically intended for high resolution, monochrome, binarymarking engines, such as imagesetters and platesetters. It is typically2400 dpi (dots per inch), color separated, screened output. The formatof the generated auxiliary output data is typically used for proofers;it may be 720 dpi, contone, color managed, composite. Both formats aregenerated at the same time.

An advantage of the invention is that the performance of the system issignificantly improved. This is especially important because formats ofimaging devices are increasingly getting larger and larger. Theinvention allows to maintain acceptable throughputs on standardhardware, and to obtain higher throughputs on faster hardware.

Moreover, only one renderer is required, whereas the method disclosed inU.S. Pat. No. 5,625,766, mentioned above, requires two differentrenderers, a low resolution one and a full resolution one.

Preferably, the data for the proofing device are generated from the highresolution screened data intended for the main output device, byprocessing the screened data; this may involve descreening, zooming,color managing the screened data. This offers the advantage that theproofer data are completely consistent with the main output data.

Further advantages and embodiments of the present invention will becomeapparent from the following description and drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described with reference to FIG. 1, which is used toillustrate an embodiment in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

In a preferred embodiment of the invention, the output data of therenderer is divided into a plurality of bands. This is illustrated bymeans of FIG. 1. FIG. 1 shows output page data 21-28 of eight pages thatwill be printed on a single sheet by an offset press. If e.g. a leafletis printed, customarily several pages of the leaflet are printed on asingle, large sheet and they are arranged, by a process calledimposition, in such a way that after printing, folding and possiblycutting the order of the pages in the final product is correct. Thesingle large sheet is, in imposition terminology, called the flat. Theoutput data 10 that correspond to the flat can have a very large size,especially after the screening step. In the embodiment illustrated bymeans of FIG. 1, a plurality of bands 11-14 constitute the output data10, in such a way that each band 11-14 contains output page data 21-28of two adjoining pages, e.g. band 11 contains page data 21 and 22. Ingeneral, a band may cross page borders. Usually, a band will be muchsmaller than a page; the size of a band may be determined by theavailable amount of memory in the renderer. In general, a band 11-14covers a subset of the output data 10, so that all output data 10 belongto exactly one of the bands 11-14 and so that the data of all bands11-14 together constitute the output data. The output data can also bedivided into a plurality of bands if no pages are used, such as forpackaging applications where the output data contain basic data that arereplicated via a so-called step-and repeat operation.

Preferably, the invention is implemented by means of a special mode inthe renderer that allows for the generation of bands. E.g. the CPSIrenderer from Adobe can be configured in such a way that, instead ofgenerating, as is customary, a whole color separation, color per color,the output data are generated for a first band for all different colors,then for a second band for all different colors, and so on; the bandsize can also be configured. A particular embodiment of the inventionfor color output is as follows. Initially, a first band of cyan isgenerated, followed by a first band of magenta, a first band of yellow,a first band of black, and optionally first bands for each separatedspot color. After all the separations for the first band are generatedin memory, the proofing processing (recombination, descreening, etc.)starts working on the first band and may store the processed proofingdata on disk, or, alternatively, send it immediately to the proofer.Then, the process is repeated to generate a second band, and so on untilall data are generated.

Preferably, the output data as generated by the renderer for thesuccessive bands are appended to each other, for each color, and theappended data are sent to the main output device, so that the mainoutput device receives a set of appended data for each color.

It is preferred that the data in the second output format, intended e.g.for a proofing device, are generated from the data in the first outputformat for the main output device, band per band; this can be performedin different ways. In a first embodiment, generating the data in thesecond output format includes resampling the data in the first outputformat, as described e.g. in EP-A-1 139 654. In a second embodiment,generating the data in the second output format includes descreening thedata in the first output format, i.e. the binary, screened data in thefirst output format are converted to a contone value. This can beillustrated by the following very simple example, wherein the data inthe first output format are 2400 dpi and those in the second format 600dpi. The 2400 dpi binary data are divided in squares of sixteen bits,i.e. 4×4 bits. Suppose that in a square of 4×4 bits four bits are set,i.e. have a value 1, and twelve bits are zero. The contone value forthis square is then 256*4/16=64=(40)_(HEX) in hexadecimal. This is thenrepeated for the next square of 4×4 bits.

Possibly, an additional action is performed in the border area between afirst band and a second band, adjoining to the first one, in order toensure a correct transition between both bands for the data in thesecond output format. Data in the first output format for the borderarea may then be stored, preferably in memory, to calculate the data inthe second output format in the border area. In the very simple examplediscussed above, if the border between the first and the second banddoes not coincide with sides of the 4×4 squares (but divides e.g. thosesquares in halves), then, when processing the first band, the data inthe first output format of those squares on the border may be storedtemporarily, and used subsequently in calculating the data in the secondoutput format for the second band.

The data in the second output format may directly be sent to theproofer, e.g. band per band, or they may be stored, e.g. on disk.

The invention is not limited to the embodiments described above. In caseof color output, other colors may be used; the order of the colors mayarbitrary. The invention is also applicable to black-and-white output.The invention may also be applied to other devices than a main outputdevice and a proofer.

Having described in detail preferred embodiments of the currentinvention, it will now be apparent to those skilled in the art thatnumerous modifications can be made therein without departing from thescope of the invention as defined in the appending claims.

List of Reference Signs

-   10: output data-   11: band-   12: band-   13: band-   14: band-   21: page data-   22: page data-   23: page data-   24: page data-   25: page data-   26: page data-   27: page data-   28: page data

1. A method for rendering input data simultaneously into output data ina first output format and in a second output format, the methodcomprising the steps of: defining a plurality of bands constituting saidoutput data; for each specific band out of said plurality of bands: i)generating by a renderer from said input data first output data for saidspecific band in said first output format; ii) generating, from saidfirst output data, second output data for said specific band in saidsecond output format sending said output data in said first outputformat to a main output device; and sending said output data in saidsecond output format to a proofing device.
 2. (canceled)
 3. The methodaccording to claim 2 wherein said main output device is either animagesetter or a platesetter.
 4. The method of claim 1 wherein saidfirst output data for said specific band comprises data for a pluralityof colors.
 5. The method according to claim 1 further comprising thestep of: descreening said first output data for said specific band. 6.The method according to claim 1 further comprising the steps of:temporarily storing a first portion of said first output data for saidspecific band wherein said first portion adjoins data for anotherspecific band out of said plurality of bands; using said first portionof said first output data for said specific band for connecting saidsecond output data for said specific band to said second output data forsaid other specific band.
 7. The method according to claim 1 furthercomprising the step of: appending said first output data for eachspecific band out of said plurality of bands, thus obtaining said outputdata in said first output format.
 8. A system for processing datacomprising: means for defining a plurality of bands constituting saidoutput data; for each specific band out of said plurality of bands: i)means for generating by a renderer from said input data first outputdata for said specific band in said first output format; ii) means forgenerating, from said first output data, second output data for saidspecific band in said second output format means for sending said outputdata in said first output format to a main output device; and means forsending said output data in said second output format to a proofingdevice.
 9. The system according to claim 8 further comprising saidwherein said main output device is an imagesetter, a platesetter or aproofing device.
 10. (canceled)
 11. A computer program running on acomputer for rendering input data simultaneously into output data in afirst output format and in a second output format, the computer programcomprising: defining a plurality of bands constituting said output data;for each specific band out of said plurality of bands: i) generating bya renderer from said input data first output data for said specific bandin said first output format; ii) generating, from said first outputdata, second output data for said specific band in said second outputformat; sending said output data in said first output format to a mainoutput device; and sending said output data in said second output formatto a proofing device.
 12. A computer readable medium comprising programcode when run on a computer for rendering input data simultaneously intooutput data in a first output format and in a second output format, for:defining a plurality of bands constituting said output data; for eachspecific band out of said plurality of bands: i) generating by arenderer from said input data first output data for said specific bandin said first output format; ii) generating, from said first outputdata, second output data for said specific band in said second outputformat; sending said output data in said first output format to a mainoutput device; and sending said output data in said second output formatto a proofing device.
 13. The computer program of claim 11 wherein thestep of sending said output data in said first output format to a mainoutput device comprises sending said output data to an imagesetter, aplatesetter or a proofing device.
 14. A computer program product forrendering input data simultaneously into output data in a first outputformat and in a second output format, the computer program productcomprising: first program instructions for defining a plurality of bandsconstituting said output data; second program instructions for, for eachspecific band out of said plurality of bands: i) generating by arenderer from said input data first output data for said specific bandin said first output format; and ii) generating, from said first outputdata, second output data for said specific band in said second outputformat; third program instructions for sending said output data in saidfirst output format to a main output device; and fourth programinstructions for sending said output data in said second output formatto a proofing device.
 15. The computer program product according toclaim 14 further comprising a computer readable medium wherein saidfirst, second, third and fourth program instructions are recorded onsaid medium.
 16. The computer program product according to claim 14wherein said main output device is an imagesetter or a platesetter. 17.The computer program product according to claim 14 wherein said firstoutput data for said specific band comprise data for a plurality ofcolors.
 18. The computer program according to claim 14 furthercomprising: fifth program instructions for temporarily storing a firstportion of said first output data for said specific band wherein saidfirst portion adjoins data for another specific band out of saidplurality of bands; and sixth program instructions for using said firstportion of said first output data for said specific band for connectingsaid second output data for said specific band to said second outputdata for said other specific band.